When many electronic systems are operated at the same time, the amount of electrical power consumed by the systems can be relatively large. For example, a computer server “farm,” incorporating hundreds or thousands of computers in a single enterprise or location, consumes a considerable amount of electrical power. The electrical consumption can, thus, be a significant operating cost for the enterprise. It can be advantageous, therefore, to measure and keep track of the electrical power usage of each electronic device or system in order to manage the electrical power consumption of the enterprise.
To determine the power usage of each electronic system, values for the current and voltage generated by a power supply for the system are determined. The power used by the system is calculated from these values. To. obtain these values, the generated current and voltage are measured. These measurements, particularly regarding measurement of current, add to the load on the power supply, due to the use of a sense element, such as a current sense transformer or resistor, in the current path. The sense element measures the voltage drop across it. The voltage drop is relatively low, so it needs to be amplified for proper measurement, thereby requiring additional circuitry. This technique can be difficult to implement because of the need for complex analog circuitry. Additionally, the efficiency of the power supply is reduced due to power loss in the sense element. Furthermore, the added circuitry or components take up valuable space within the electronic system.